1. Field of the Invention
Embodiments of the present invention relate to field of display manufacturing technology, and more particularly, to a display back plate and a manufacturing method therefor, and a display device.
2. Description of the Related Art
A small molecular organic light emitting diode (OLED)-based organic light emitting display device or a polymer light-emitting diode (PLED)-based organic light emitting display device becomes mainstream products in the field of display, due to their characteristics of self-illumination, quick-response and wide viewing angle, etc.
In the OLED-based or PLED-based organic light emitting display device, a display back plate generally comprises a TFT array substrate, a pixel define layer (PDL) arranged over the array substrate, several organic light emitting units (such as OLEDs or PLEDs) defined by the pixel define layer, and a packaging layer as the topmost layer, wherein the organic light emitting unit is generally consisted of a positive electrode, a hole transport layer, a light emitting layer, an electron transport layer (ETL) and a negative electrode. Moreover, service life of the organic light emitting display device mostly depends on whether or not the organic light emitting units are in touch with water vapour and oxygen. If packages of the organic light emitting display devices are not adequate, some components in the air, such as water vapour and oxygen, may permeate into the organic light emitting display devices, which increases a performance function of the negative electrode of the organic light emitting unit, thereby adversely affecting service life of the organic light emitting display device. In addition, water vapour will make a chemical reaction with the hole transport layer and the electron transport layer, which adversely affects the service life of the organic light emitting display device. Accordingly, adequate packages of these organic light emitting units separate respective functional layers in the organic light emitting display device from components in the air, such as water vapour and oxygen, which can effectively prolong the service life of the organic light emitting display device.
The existing organic light emitting display device is usually hermetically packaged within an inert gas environment such as N2. Drying agent is provided over the packaging layer to prevent water vapour in the air from permeating into the organic light emitting components, so as to effectively prolong the service lifes of the organic light emitting components. However, some parts, such as thin film transistor on the array substrate, color film, etc., inside the organic light emitting display device can generate gases, liking water vapours. Water vapours generated from these interior parts still adversely affect the service lifes of the organic light emitting components.